Johnson Pump MDR Series Instruction Manual page 19

6.0 Trouble shooting chart
Problem
No flow
Underfeed
Excessive power
Excessive vibration or
noise
MDR/EN (0909) 1.0
Possible cause
Air pockets in suction lines
Lack of prime (when suc-
tion head is negative)
Air pockets inside the
pump
Insufficient suction head
Slipping magnet coupling
Wear or damage of parts
No liquid in the pump
Air entrainment or air
pockets
Run reverse
Excessive piping loss
Impeller is clogged with
foreign materials
Excessive specific gravity
and/or viscosity
Excessive wear of pump
parts
Excessive wear of motor
bearings
Wear or damage of parts
Short of head
Impeller is clogged with
foreign materials
Remedy
Check piping of suction
lines and work out all air
Prime again
Work out all air
See section 2.2.1
Excessive specific gravity
and/or viscosity - check
against original specifica-
tion (see point 2.7)
Replace parts
Check liqud level in the
tank. If a foot valve is
installed on the suction line
make sure that it is properly
sealed. Fill the pump again.
Check joint sections of suc-
tion lines. Work out all air
Check direction of rotation
Reduce suction line length
or increase diameter
Remove foreign materials
Check viscosity and specific
gravity against pump per-
formance (see section 2.7).
Replace parts
Replace bearings/motor
Replace parts
Increase discharge head
(see section 2.3)
Remove foreign materials
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